Currently, in the electronics art, delay lines are employed for a number of functions. For example, delay lines can be employed in particle study apparatus of the Coulter type such as is described in U.S. Pat. No. 2,656,508. The delay line would be employed as a part of circuitry used to improve the Coulter type particle detector by correcting for counting errors. In such applications, the delay line must have an analog characteristic. That is, it must delay signals without altering them in any way. Furthermore, in many applications, the delays must be for an appreciable length of time. LC networks generally can be used to provide analog delays, however, LC networks become extremely complex, bulky and impractical to use when long delays are required.
Long delays of analog signals can be provided by use of charge transfer devices currently available. The signal to be delayed is sampled and the sample stored for a period of time in a charge transfer storage register. Enough samples of the signal are taken so that the signal can be recreated from the samples. Of course, the signal duration must be relatively fixed in order to determine the number and relative timing of the samples, and the number of storage locations. If these are not known, a great many samples must be taken at a high repetition rate, and a substantial number of storage elements provided to store the samples. This again will result in a product which will be unacceptable due to its size and/or cost.
Statistically it can be shown that in any relatively uniform signal waveform which does not have sudden inflections, only a certain number of samples of the signal need be taken in order to reproduce the signal waveform, no matter what the signal duration. If the duration of the signal to be delayed is known, then a minimum number of samples and storage areas would be necessary. If a number of signals in sequence are to be delayed and they have a somewhat similar duration, an average number of samples to be taken in a period of time and stored can be established. If, however, the signals to be delayed consist of a series or train of signals having similar duration, and due to some change, these are followed by a series or train of signals having a substantially different duration, longer or shorter, establishing a fixed number of samples in a period of time and a fixed number of storage locations may not allow the recreation of the original signal, delayed in time.